Boundaries
by Griever11
Summary: Set post 4x10 - Cuffed. Castle and Beckett navigate through their tangled web of emotions while trying to solve a crime in a sex club. For Lou. My entry for the Castle Winter Ficathon
1. Chapter 1

For Lou, on her birthday. Love you lots!

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Kate Beckett is a little nervous.

It's not often that she feels this way, senses on high alert, fingers curled into a fist under the table in an attempt to soothe her nerves. She's in a short dress and can feel the cool breeze from the air-conditioning that swirls around her bare legs. Her hair is hanging loose in soft curls around her shoulders, purposely styled mere hours before, and she's wearing a lot more makeup than she usually does for work. It reminds her of when she was in Vice, a little out of her own skin and she doesn't like the feeling. She tries to calm herself, keeping the slight smile on her lips as she reminds herself that she's only playing a part.

Next to her, much to her chagrin, Castle sits perfectly still, poised and calm as if he's done this a million times. It bugs her that he seemed to fall into the part so easily, taking it all in his stride. She's the cop here not him, but here she is, nervous twitching in her eye and it's as though being interviewed to be allowed to enter one of the city's most exclusive swingers club is something he does on a daily basis.

A swingers club. _God._

Not for the first time this evening, she wonders just how she manages to find herself in these uncomfortable situations time and time again. It's only been about two weeks since the incident with the tiger and the cuffs, and now she's pretending to be a married swinger.

She blames Castle.

Her eyes cut to his profile, glaring at him in silence. The case they're working on involves a string of dead bodies that had turned up around the city, all married couples and all murdered in the same style - which led them to conclude that they were after a serial killer.

Ryan and Esposito, after very many exhausting days of witness questioning and chasing down leads, had found out that all the victims were swingers who'd frequented the same swingers club - The Bowery - within the last month or so.

Unfortunately for them, getting a search warrant for the club had proven to be difficult, and when Ryan and Esposito had started questioning the employees, they'd come up empty handed. That's when Castle had chimed in with his _brilliant_ idea.

So despite a lengthy argument with Captain Gates about the sheer absurdity of his plan, she still found herself sitting in a small interview room at the club, pretending to be married to Castle. Pretending to be married to Castle _and_ looking to have sex with other married couples. Of all her undercover stints she's participated in, this is hands down, the most complicated.

Her relationship with Castle is in a weird place, partners toeing the line between being really good friends and something... _more_. The profession of love that fell from his lips as she lay bleeding out at Montgomery's funeral festers in the back of her mind; the guilt of her lie and the failure to acknowledge his words fueling her many sleepless nights.

It's not like she doesn't have feelings for him. It's the complete opposite, actually. It's just that she thinks Castle might be her _one_ , and she's not sure if she's ready for that just yet. He's all but promised that he'd wait for her for as long as she needed, and it gives her hope that someday they'll be able to have their happily ever after. It does, however, serve as a reminder that she's being completely unfair to him for as long as she keeps pretending she doesn't know how he feels about her.

And now, sitting in such close proximity to him with the lingering scent of his cologne in the air and having to pretend to be married, especially after being cuffed to him for hours two weeks ago, it sets her heart aflutter. It's like she's on a see-saw of emotions, bouncing back and forth between maintaining their status quo and giving in, kissing him senseless.

She groans at her predicament and it causes Castle to turn to her. He must have mistaken her frustration as being connected to the case and he smirks at her, an annoying glint in his eye.

"It'll be fine, Beckett. It's just pretend," he says. "Let me do all the talking, you just sit there and play nice."

"Yeah, because you probably do this sort of thing every day, don't you?" she snaps at him and as the words leave her mouth, she notices that his smile falters, forehead creasing as his eyebrows furrow. Her gut churns with regret at her words. She hadn't meant them with any malice, but she thinks she may have hurt him a little.

"I'm not that kinda guy, Beckett," he mumbles."I might have been ... a little indiscreet in my younger days, but I'm not like that anymore. I'm just trying to help."

Beckett swallows and opens her mouth to apologize. She knows. She _knows_ he's not the same man who'd weaseled his way into her life four years ago. She'd let her frustration with her own issues get the best of her and she'd lashed out at him. Castle had become one of the few people she trusted with her life, and he didn't deserve the derision that had colored her earlier words.

But before she gets the chance to speak, the door in front of them swings open and a woman strides in, heels clicking against the marble floor. She's wearing a gorgeous knee-length red dress, cut low enough to showcase her ample cleavage.

The woman smiles, warm and friendly before taking her place in the chair opposite them. She has a clipboard in her hand and she sets it down on the table before speaking.

"Hi, my name is Francie and I'm in charge of making newcomers feel welcome when they visit us for the first time. How are you, Mr. and Mrs. Rodgers? Are you feeling alright?"

Beckett mentally smacks herself; she thought she'd had her emotions under control, but Francie had managed to pick up on her nervousness instantly. Her eyes dart to Castle, fingers still clenched beneath the table. Castle turns to her, a warm smile on his face - not a single worry line in place and his hand reaches out to palm her knee, a soothing balm on her frayed nerves.

"Oh, Becca's just a little nervous, that's all. We've never done anything like this before." His voice is steady, deep and comforting. He's still staring at her, and she clears her throat before turning back to Francie.

"I'm okay, really. Just a little out of my comfort zone."

Francie nods and and picks up the clipboard. "I understand. As long as this is something both of you want, I have no problems with it. The Bowery is a place of mutual consent, and we do not want any misunderstanding about what goes on in here. Everyone who comes to the Bowery is here for a good time, and we have a zero tolerance for anything otherwise."

Beckett feels the hairs at the back of her neck prickle and stand on end. The tone of her voice implies that something unsavory had happened recently, necessitating the warning, and Beckett perks up at the rush of excitement that comes with her finding a lead for a case. Her fingers drum a rhythm against the flesh of her knee; she's impatient now, eager to get on with the proceedings so she can get to the bottom of the case.

Francie however, kept speaking, well practiced at reciting the words she now relays to them.

"We pride ourselves in the type of clientele that we allow here, I'm sure you understand why. It looks like you two seem perfect for us, but for the sake of formalities, please tell me a little about yourselves and why you've come here today."

Castle speaks again next to her, and she's grateful that he's taking the lead this time. His natural charm will work in their favor, and as he recites the background information that they'd been fed for their respective covers, Francie's posture eases, shoulders relaxing.

He weaves a tale about their fairytale meeting, their enchanted wedding and she sees Francie eat it all up. The low baritone of his voice explains that they've been married for a little over three years and while they still love each other, they're beginning to feel a little bored and needed a little spice in their life. Castle's a natural storyteller and when he ends his fictional tale, Francie has a hand on her heart, a wistful look on her face and Beckett knows they're in.

"That is lovely, you two. I can't imagine you'd cause any problems here," she croons. She turns the clipboard around to face them and a long painted fingernail scores the bottom line of the paper. "Just need your signatures here, have a read of the usual rules regarding discretion; what goes on, who you see here, of course. And it's an upfront payment of a two hundred dollars for couples."

Beckett's eyebrows arch in alarm, not expecting the steep price for entry. She doesn't have that kind of cash on her, and her credit cards have her real name on it, and so would Castle's. Her fingers unfurl and dig into the clutch on her lap, but Castle's wide palm covers her hand, stilling her movements.

She looks at him, tries to warn him with her eyes about not using his credit card in case he hasn't thought about it. He reaches into his suit jacket and she's about to protest, but he merely grins and hands over a wad of cash to Francie.

Okay, that works too. Of course he has two hundred dollars in cash casually stashed in his jacket. _Of course_.

Castle scribbles his fake signature on the dotted line and slides the clipboard over to her. She makes a quick scan of the rules, making sure they're not signing anything out of the ordinary and signs her fake name as well.

"Well, we're all done here. If you need some time, feel free to stay here as long as you want. When you're ready, just go through the door, and follow the corridor straight into the common room. I hope you enjoy your time here." Francie says, pushing her chair back and standing up. She picks up the clipboard, winks at them and disappears behind the door.

Beckett lets out a breath as relief washes over her and clears her throat.

"Well that was terrifying," she mutters. "Being interviewed to be allowed to have sex, I mean."

Castle chuckles, hearty and full of mirth. "They're just covering all their bases, Beckett. Can't have dirty creepers into such a fancy establishment, can they?"

She cocks her eyebrows at him and rolls her eyes. "Well, we're only here because there's a murderer on the loose among them - I'm pretty sure that's up there with 'dirty creepers', Castle."

Castle purses his lips, eyes squinting as a thoughtful look crosses his face. "Huh, yeah. I guess that's worse than dirty creepers."

Beckett scrapes her chair back and stands up as Castle does the same next to her. Her dress swishes at her knees, soft and silky against her skin. She'd opted for a simple blue dress, modest compared to some of the dresses she's chosen for her other undercover operations, but it seems to please Castle nonetheless, if his expression is anything to go by.

"Have I told you how beautiful you look tonight?" he asks, cheeks dimpled in a wide smile. He holds his elbow out to her, and she loops her own arm through it.

"You did when you picked me up from the precinct," she mumbles, unsure of how to take the compliment. She does, however, respond with a similar sentiment. "You look pretty good too, Castle. Very ready to go have sex with a bunch of married strangers."

He laughs at that and it makes her lips curl upward too. She keeps the smile on her face as he leads them through the door and down the corridor Francie had instructed them to go through.

They pause before a set of double doors, a sign with fancy lettering spelling out 'The Bowery' on top of the doorframe.

They look at each other and suck in a breath at the same time. Turning back towards the double doors, they both reach out and push, stepping past the threshold, letting the doors swing shut behind them.

What greets them is nothing she'd seen before and it causes a warm blush to rise up to her cheeks. It's a big room with dark lighting, a kaleidoscope of color with bits of blue, purple and green swirling before her eyes. Music pulses through giant speakers all over the room, seductive and enthralling at the same time.

And the people.

There are so many people in the room, close to thirty, she thinks, and almost all engaged in activities that are more commonly conducted in private. A woman is in a corner, on her knees before a man whose eyes are shut, hands fisting in her hair as she pleasures him.

Kate Beckett is far from a prude, but she looks away and scans the rest of her crowd. Her eyes catch sight of a group of naked people having sex on a lounge in the middle of the room and she averts her eyes, turning around to look at her partner instead.

He looks down at her, muted amusement in his eyes, but he's also sporting the same hint of blush on his cheeks. Beckett's somewhat relieved he's just as affected as she is and she licks her lips, feeling more out of place than she's ever felt in her entire life.

"You okay?" Castle asks, straightening his arm so her hand falls away from the crook of his elbow. He's always been able to read her, something she's been both annoyed and impressed by. It's no different this time round and he seems to sense that she's not quite at ease here.

He steps around so he's standing in front of her, shielding her from the rest of the room. "Um, we can just go, if this is too much. I mean, it's ah, pretty full on."

He isn't being cocky about noticing her discomfort, something she's grateful for. One hand comes around to splay wide on her back, while the other curves around her shoulder. A weird thrill of want travels through her at the contact. It's sweet, actually. He's trying to protect her from the rest of the people in the room and her blood warms at the sentiment.

"Yeah, I'm okay. We can stay. We have a job to do."

She smiles at him, her fingers plucking his hand from her shoulder and curling around his large digits so they're holding hands, very reminiscent of when they were handcuffed together.

She recalls a line he used during that case and she grins at him, tongue peeking out in mischief as her eyes meet his.

"You know what I love about working with you?" she asks, echoing his words from back then. His eyes twinkle in delight, no doubt remembering the same conversation she's repeating to him right now. "You always take me to the most charming places."

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 **tbc**

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Twitter: estheryam  
Tumblr: griever11


	2. Chapter 2

The music reverberates around her; strong bass beats beneath the techno-electric melody pulsing from the giant overhead speakers. She's always been a creature of rhythm and Beckett is itching to dance, to sway with the crowd and get lost in the music - only, she's not Kate Beckett: awkward dancer, right now - she's _Detective_ Beckett and she's technically still on the clock. Sighing, she licks her lips and raises a finger to push against Castle's shoulder, making him turn away from her to face the vast expanse of the common room.

The fingers of her right hand are still intertwined with his, but she doesn't slip them out of his grasp like she knows she should. They're meant to be married - married people hold hands. It's normal, and it's also convenient. She doesn't want to lose him in this crowd, after all. It would be inefficient to spend what precious time they have here hunting him down among the throng of people milling about.

Castle tugs on her hand, urging her to move and she follows him in silence. She's happy to let him take the lead, preoccupied with absorbing her surroundings, taking mental notes as they walk through the display of hedonism around them.

There's a staircase by the side of the room, next to a packed dancefloor, that spirals downwards into what she assumes are more private quarters for those less inclined to be exhibitionists. There are beds scattered in random spots around the room, mostly hidden behind billowing white canopies. She can only just make out shadows flickering in and out behind the sheer drapes and she swallows; nope, she doesn't want to know. At all.

After a lot of careful maneuvering and finally side-stepping past a group of rather amorous couples heading downstairs, they manage to make their way to the bar. The secluded area glows with fluorescent lights, LED strips embedded under the glass surface. The blue and white that emanates from the countertop give it an ethereal atmosphere and Beckett's a little impressed by it all.

Castle crowds in next to her, solid and warm pressed up along the side of her body and she struggles to remain stoic and unperturbed. The gyrating bodies on the dancefloor and the shameless nudity parading around make her tingle all over, blood rushing through her veins, warming her from the inside out. Add that to the fact that Castle is _right there_ , a constant comforting presence skirting her orbit - ugh, as soon as she gets the information she needs, she's hightailing out of there and taking a very, very cold shower.

"Drink?" Castle's voice hums in her ear, his breath a soft caress over her skin and awareness once again flares from within. She bites her lip, ignores the sizzling in her veins and tamps down the crackle of desire, instead focusing on the barman and the task at hand. Information, they need to gather information.

"We're still on the clock, Castle," she mutters, low enough for him to hear, but otherwise, the music does a good job of drowning out her words from the other patrons who could potentially eavesdrop on their conversation.

"Ha, actually _you're_ on the job. I'm just the ... company," he waggles his eyebrows at her, a cheeky grin on his face. His fingers untangle from hers and he waves the barman down, wiggling his digits in the air. " _And_ we gotta play the part, _Becca_. We're just a couple looking to have fun. You remember what that is, don't you?"

A surge of annoyance ripples through her at his slight jab. She doesn't appreciate the implication of his words - hasn't she shown him over the last few months just how much fun she could be?

They've had movie nights together, dinners out - hell, she's even humored him and accompanied him to that ridiculous 'haunted' house, for God's sake. She thought she was doing well trying to open up to him, and yet...

"I'm not here to have fun, Castle. I'm here to do my job," she hisses through her teeth and she takes a step away from him, putting some space between them.

Castle's eyes cloud over for a quick second, but she can't find it in herself to care about his feelings right at this moment. She's frustrated, uncomfortable, and all she wants to do is go home and soak in her bath - maybe with her shower head against her-

"And what can I do for you lovely beings tonight?"

She's startled out of her thoughts by the bartender approaching them and she blinks, mesmerized by the glitter adorning the man's almost naked upper body. Wow. Shiny.

"Whiskey, neat for me - and my dear wife, what will you be having, darling?"

Beckett thinks there's a hint of disdain in his voice as Castle speaks, but she brushes it off and gets her mind sorted out, getting into Detective mode.

"Just a lemonade, please. Hey, we're new here and we're just wondering if there's ... anything we should know," she pauses, flutters her eyes at the barman in what she hopes is in an enticing enough manner. "Y'know, about the people here. Regulars, the unwritten rules - what to do and what not to do?"

In her peripheral vision, she sees Castle inching towards her, ignoring the fact that she'd stepped away from him for a reason. He thinks he's being so sneaky, like a character from one of his stupid games - but he's a big man, a little clumsy and she has to refrain from rolling her eyes at his antics.

The barman gives her a weird look, probably sizing her up but relents eventually, a broad smile splitting across his face. "You are going to have so much fun here! Don't worry about anything or anyone, there are no rules, if you know what I mean."

He winks at her as he finishes talking, and doesn't hide the slow drag of his gaze down to her chest, leering at her. Beckett shudders at his attention, feeling dirty all of a sudden. Castle, as if he can read her mind, wraps an arm around her shoulders and despite her seeking space from him earlier, she welcomes the contact now.

The barman raises his eyebrows, eyes wide as if to say 'Okay, backing off now' and busies himself with their drinks. When he's done, he slides the two glasses over the counter to them. Castle's hand, the one not currently draped around her, encompasses the entire tumbler of whiskey, and as he lifts it to his lips, Beckett marvels at the way his large fingers curl around the glass.

It's not the first time she's seen his hand obviously, but she's never really paid attention before now. The same hand that had punched the living daylights out of Hal Lockwood is also responsible for the magical words he weaves on the pages of his books. Powerful, yet gentle - much like the rest of him, if she's being honest. She finds herself wondering just how gentle he can be, how his hands would feel against her skin; warm and smooth. Or is his skin a little course-

"You just gonna stare at me, or are you gonna drink that, Beck-Becca?"

Her eyes flick up to his, and the moment she sees the knowing smirk playing on the corner of his lips, she knows she's been caught. Her cheeks feel hot and she's grateful for the distraction that her glass of lemonade provides.

"Yes, shut up, I'm drinking," she mumbles, downing the entire thing in one go. She allows the liquid to travel down her throat, hoping the cool drink will counter the heat of the rising blush in her cheeks.

"Lucky they chose a cover name so similar to yours, huh?" Castle says. "Helps when I forget we're under-"

"Oh, my God! Can you shush?" Beckett scowls at him and ducks under the arm around her shoulder, removing herself from being plastered to his side. The music's loud, yes - but it really doesn't give him a free pass at broadcasting the real reason they're here. "Let's just...work, okay?"

The barman sidles back over to them to collect their now empty glasses. Beckett thanks him with a smile, but before he moves away again, Castle leans over the counter and crooks a finger at him. The barman comes forward and the two men huddle in, heads almost touching as they meet over the bar.

Beckett grits her teeth, jaw set tight - just what _is_ he doing?

"Hey man," Castle begins. "If the missus and I, uh," he pauses and licks his lips for sheer measure. "If we want an experience that's a little bit more, um ... let's just say, ah, _50 Shades of Gray_ , who do we go to?"

Oh, okay, she'll admit that it's actually a good move on Castle's part. All their victims, in addition to being, well, _dead_ , had a couple of other things in common - strangulation marks, rope burns, and lashes across their backs as if they'd been whipped.

Ryan and Esposito, after hours of research, decided that while they could have been consistent with being tortured to death, were more inclined to believe that they had all been willing participants in the S&M culture.

The barman's eyes light up at Castle's question and Beckett comes closer, not wanting to miss any information that may be pertinent to their case. The barman, however, mistakes her movement as excited anticipation and he cackles loudly.

"Ah, an adventurous pair, I like it!"

Castle grins and nods, smooth as ever, not even the slightest bit disturbed. "We heard from friends of ours that if that's the kind of fun we like, this is the perfect place! Mike said he knew a couple who came here - the Leroys, I think, who really enjoyed themselves."

At the mention of their latest victim's surname, the barman's expression darkens and he crosses his arms over his chest, eyes narrowing at Castle.

"The...Leroys? How do you know them?"

Alarm bells go off in Beckett's head; she doesn't want to spook the guy and blow their covers. It's clear that he's hiding something, or at the very least knows something about their demise. She clears her throat, trying to divert his attention away from Castle.

"Oh, just through our mutual friend - Mike. He's the one who, ah, said that we have similar _interests_ and told us to come here. We don't know the Leroys personally, no," Beckett chimes in.

Castle's hand rests low on her back and it's as if his natural charm and confidence is flowing straight from him through her. She leans into his wide-spread fingers and she turns to him as she lets out a forced giggle, hamming it up for the barman.

"We're just here to have a good time with each other," she insists, eyes trained on her partner's amused ones, bright blue despite the low light around them. She keeps her gaze steady, hopes that it convinces the barman of their ignorance.

"And also, _others_ ," Castle adds, winking at her and she has to stifle a groan. He's enjoying himself far too much for her liking, but it seems their play-acting worked. The barman chuckles and flicks the rag he used to wipe down the bar over his shoulder.

"Ah well, you wanna speak to Dylan over there then. I assure you, you will not be disappointed."

"Okay, great. Thank you so much," Beckett says, before taking Castle's hand again. She starts to move, but Castle doesn't budge.

"What now?" she asks, trying not to let her exasperation show.

"Should we tip him?" Castle nods in the direction of the barman as he reaches into the bowl of nuts on the counter. He examines the large nut he fished out of the bowl and grimaces. "And should I eat this? Is it sanitary you think?"

Beckett sighs. "Whatever you want, c'mon. Let's go."

"No, but if it turns out to be a good lead, he deserves a big tip! And I'm hungry - I should eat this."

Beckett doesn't know if Castle's being more annoying than usual tonight, or if it's the fact that she's frustrated and entirely out of her skin here - but god, he's really getting on her nerves tonight.

"Ugh, can you stop worrying about your big tip and just shove that nut in!"

She regrets it the moment she hears the words leave her lips. Castle's jaw drops open as the sentence registers in his brain. His mouth opens and closes, speechless, but his eyes are bright with mirth, probably on the brink of calling her out on her slip up.

"Shut up," she mutters, her thumb and forefinger grabbing a nut from the bowl and flicking it at Castle's giant head. "Just shut up, let's go get Dylan."

She drags him away, weaving in and out of the crowd of people until she reaches the dancefloor.

Dylan is shirtless, dancing among two women and another man, looking as if he's having the time of his life. His dirty blonde hair is plastered to his forehead, but it looks good on him despite the sweat trickling down the side of his face. The women's hands traverse the muscled expanse of his chest, fingernails dragging up and down his torso as they bump and grind against him.

Castle lets out a moan of disgust next to her, and she turns to him, curious. He's clenching his jaw, the sharp angle causing shadows to play over his face. It makes him look dark and dangerous, mysterious.

The hand she's holding squeezes hers a little tighter and she purses her lips, unsure if she should be flattered or annoyed at Castle's display of possessiveness.

"Uh, Beckett, looks like he's busy. Let's go, we can come back later." His voice is a few decibels lower than usual, gruff and unfamiliar.

"Aw, c'mon, he's harmless. The faster we get through this, the faster we can go home."

Ignoring Castle's protests, she leaves him on the edge of the dance floor and stalks towards Dylan. She works her way through the crowd of gyrating bodies, adding a little jaunt to her steps as she sways to the beat of the music. She keeps her eyes on her mark as she dances, twisting her hips, running her hands down the side of her own body.

She twirls, hair flaring out behind her as she allows the music to takeover for a moment. She catches a glimpse of Castle in her peripheral vision and she's taken aback by the intensity of his gaze. He's not just staring at her like she expected, doe-eyed and wanting - instead he's actually studying her, tracking her every movement with a solemn look on his face.

 _O-kay._

She turns back around and finds herself already within an arm's length of Dylan's dancing group. Just as she predicted, he notices her pretty quickly and his eyebrows arch in an invitation. His hands reach out to her, sinewy muscles rippling under the strobing lights and he beams. Taking his cue, she moves towards him, takes his hand and joins his posse.

"Hi there, you must be new," his voice is husky in her ear as he pulls her against him so her back is pressed up against his chest. His hips sway from side to side and he places a hand on her waist to guide her with him so they're moving together to the beat.

The other man slides in, tapping his feet in time on the floor, every step taking him that much closer to her. She's sandwiched between the two men and it's all _very_ uncomfortable. She's dirty dancing with strangers and it leaves a really bad taste in her mouth. But she has to do this - get him talking, so she grits her teeth and turns away to face Dylan.

"Yes, I am," she smiles and runs a finger down his bare chest. She flutters her eyelashes at him and brings the same finger to her mouth, dipping it in and releasing it with a quiet 'pop'. "And I was told you're just the man I'm looking for."

"The man _we're_ looking for," a voice interrupts from behind her. Beckett jumps and twists around, startled. Castle it seems, has made his way to the dance floor and is now standing before her, a steely glint in his eye, fists clenched by his sides. Beckett notes that the other man is now nowhere to be seen.

"Dylan? I'm Andrew, and I see you've met my wife, Becca."

Beckett bristles at his tone. There's a hint of anger beneath the false pleasantries and she's aware that he's steadfastly avoiding looking at her. Castle's staring at Dylan, unmoving - a solid rock among the sea of fluid dancing and Beckett's afraid that he's calling too much attention to them.

She places a palm on Castle's bicep, curling her fingers around it, her thumb rubbing circles against the fabric of his shirt in hopes of soothing him. She needs to take control of the situation soon, or their entire operation is going to go up in flames.

"Andrew _dear,_ Dylan here is gonna show us a good time like we wanted," she tells him. "Right, Dylan?"

The other man laughs out loud and shakes off the women dancing around him. "Oh, yes why of course, of course. Please, we cater to all kinds of interests here. No need to be shy about it. Wait right here, I want to introduce you to some friends of mine."

Dylan slinks away, his half naked body disappearing into the sea of people. She starts to follow him, but Castle reaches out to stop her, his hand circling her wrist and pulling her back.

"Beck-a, what the hell do you think you're doing?" Castle growls. The vehemence in his voice is completely unexpected and she blinks at him, dumbfounded.

"What are you talking about?" she snaps at him, wrenching her hand out of his tight grip. "And don't you dare do that to me again."

"I'm talking about you, waltzing right up at him without so much as a game plan - what were you going to do, seduce him into a confession? Do we even know if he's involved in this?" Castle bites back, muted anger painting his words.

Not one to back down from a confrontation, Beckett glares at him as she retorts. "We don't know for sure until we get more out of him, will we? Just what is your problem here?"

She watches as Castle's eyes slam shut and he lets out a controlled breath of air. He brings the heel of his palm up to press against his closed eyelids, sighing. "Look, I just don't - can you please not run off on your own? What if he hurt you? What if he'd taken you somewhere and I couldn't follow you and-"

"Excuse me? This, coming from _you_? Are you kidding me right now?" she snarls at him. Why is Castle being so infuriating all of a sudden? She's doing her goddamn job. He may be her partner but _she's_ the cop, and who is he to tell her how to do it?

"And also, we're not really married, in case you've forgotten. I don't need to ask your permission to do anything, much less my job - so if you can't handle the heat, just go home. I can do this on my own."

The fury is all encompassing and she sees red. This whole damn idea was his in the first place. Stupid, infuriating man. She's teetering on the edge of a possible lead that might break the case and she's not about to lose it. She gives Castle one last withering glare and turns away from him, striding across the dancefloor, whatever he's saying to her falling on deaf ears.

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tbc

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Twitter: estheryam  
Tumblr: griever11


	3. Chapter 3

Thanks to all who have read and reviewed, I love all of you!

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The first thought that crosses her mind as she descends the spiral staircase is that she shouldn't be doing this without Castle. After her mini-blow up with her partner, she'd gone after Dylan, chasing down the half-naked man as he went in search for the 'friends' he wanted to introduce them to.

When she had caught up to him, Dylan seemed unfazed by the fact that Castle wasn't with her and insisted that she make her way downstairs anyway. So here she is, despite her reservations, licking her lips as she follows him.

Her eyes have to readjust as the lights get dimmer. There's an air of mystery down here; it's darker, quieter, and it's creeping her out. She glances behind her as she reaches the landing, hoping Castle followed her but her heart sinks when she doesn't spot his familiar frame. Maybe she'd been too harsh on him. Maybe he'd really taken her words to heart and gone home.

Crap, why had she taken out her frustrations on him like she did? He didn't deserve it, even if he _had_ overreacted. Sighing, she makes her way down the corridor taking note of the closed doors along the way. She doesn't know where she's going exactly, but she's starting to think that if anyone wanted to commit murder, this little underground _sex den_ would be the perfect location.

She winces as she hears muffled moaning from behind the doors she's passing. It's not too difficult to deduce what's going on behind them and she shudders.

"Becca! Over here!"

Beckett's heart skips a beat at the sudden noise and she whirls around. Dylan's head pokes out from an open door, a broad grin on his face. "Come on in!"

She gulps and exhales slowly, nervous with trepidation. Experience tells her going in without backup is never a good idea and she's a big fan of trusting her gut. She paints a smile on her face and tries to formulate a believable enough excuse to decline his invitation - one that won't raise Dylan's suspicions but still will allow her to stick around to do more investigating.

The bottom of her dress flutters around her knees, the chill from the mild air conditioning doing nothing to ease her worries. Her fingers clench and unclench as she decides on the easiest, mostly true excuse.

"Um, sorry Dylan, I'm kinda waiting on my hus-"

She's interrupted by a heavy hand clamping down on her shoulder and for the second time that night, Beckett nearly jumps out of her skin.

"No need to wait, honey. I'm here."

Castle appears from behind her, fingers squeezing her shoulder in reassurance before he slides his hand down her arm to curl at her elbow. "Are we about to have our fun?"

To the untrained ear, he seems eager and delighted to commence whatever it is Dylan's organised for them. But Beckett knows her partner and as she takes in the grim lines on his face and the hard-edged glint in his eye, her stomach drops.

He's still upset, whether it's with the situation in general or with her, she's not sure, but the grip he has on her elbow is firm, and his voice lacks emotion. Beckett pulls her bottom lip between her teeth, about to say something to try and soothe him but Dylan's excited voice interrupts her.

"Okay, great come this way, lovebirds!" Dylan says, oblivious to the tension simmering between the partners.

They enter the room and she stumbles to a stop, causing Castle to bump into her. The walls are painted bright red and dim lighting blankets the room in a weird glow. Whips and chains adorn the walls, coiled neatly and arranged according to size and length. A coffee table in the middle of the room has a video camera on it, several silk scarves hanging off of the edge.

A swing-like contraption dangles from the ceiling in the corner of the room, right above a luxurious king size bed. The bed itself is a deep maroon, handcuffs placed on fluffy pillows on one end. There's a small bar in another corner of the room, dark and secluded, bottles of expensive looking alcohol littering the table ready to be consumed.

It's overwhelming, intimidating even, and Beckett wonders if they should just back out now. She's definitely uncomfortable, and not knowing where she stands with Castle is causing her to feel a little off kilter.

Beckett licks her lips, swallows the lump in her throat and turns to Castle. There's no amusement flickering in his eyes like she expected, instead, they're dark and stormy, and his lips are curled up in a forced smile. The hand around her elbow falls away, and the one point of contact she has with him disappears. They're not very tactile partners, hardly touching most of the time but the cold shoulder hurt and it leaves a bitter aftertaste in her mouth.

"It's everything we wanted, isn't it, Becca?" Castle, as angry as he is, seems adamant to follow through with their half-baked plan for some reason, so she goes with it.

She leans into her partner, melding into his side and her hand creeps across his back to wrap around his waist. She tells herself it's just for the cover and that she's just playing the part of a kinky, aroused wife. It has nothing to do with trying to reinitiate the contact she lost before. Absolutely _nothing_ to do with it at all.

"Oh, yes. Just like Mike said. The Leroys must have had so much fun here!" Saccharine sweetness drips from her words, all too cheery and the complete opposite to the churning turmoil in her gut.

"I told you I'd take care of you, didn't I? And here they are, Jill and Kyle!" Dylan announces, arms wide open as a young couple cross the threshold. "Alright, you guys have some fun now!" Dylan winks, blows them all a lecherous kiss and leaves, shutting the door behind him.

The newcomers appear unaffected by the presence of other people in the room, too busy being wrapped around each other. Jill's already half undressed, shirt spread open, bright red bra peeking through their embrace. She hikes a long, stocking-clad, leg up to curl around Kyle's hip and he catches her calf, guides it around him.

Something clicks and the lights dim further, throwing the room into an eerie, shadowy, red darkness. Music pipes through the surround sound system, low, steady beats reverberating around them. The handsy couple gravitates toward the bed, falling with a 'poof' onto the sheets.

Beckett gulps, unsure of what to do and her eyes flick to Castle. If the look of complete horror on his face is any indication, they're pretty much on the same page. It's not something that gives her much confidence. What have they gotten themselves into?

 _God,_ she feels like she's in a porno.

Which, really, isn't too far from the truth.

Beckett runs her fingers through her hair, grimacing at the show before her and whispers, "Um, what now?"

"I don't know. Think they'll be okay with a little _coitus interrogatus_?" Castle replies, chuckling at his own joke.

Beckett rolls her eyes but holds back from reprimanding him; she doesn't want to make the situation worse. Humor is his method of dealing with uncomfortable situations, and this definitely qualifies as that. Still, he does have a point and she nods in response.

"Okay, we'll just see if they know anything about the murders - and if not, we get out of here, okay?"

A whoosh of relief escapes from between his lips. "Okay, done."

But before they manage to do anything else, the couple on the bed pause and separate. Their chests are heaving, clothes askew and they turn to stare intently at Castle and Beckett.

"So what's your deal, you guys new to this or what?" Jill drawls. A look of intrigue flickers across her face as she notices their discomfort and she giggles. "Oh, you _are_ new to this. Don't worry, Kyle and I will teach everything you need to know. _Everything."_

They don't wait for an answer before the couple drifts together again, tongues tangling, just on the wrong side of obscene. It's so _very_ unsettling but Beckett manages to keep her calm exterior. Castle, on the other hand, turns away as he grunts, unable to maintain the same control over his gag reflex.

"Getting some water," he mumbles, making his way to the bar in the corner of the room.

She stares at him for a beat, considers joining him but then decides against it. Mission first, disgruntled partner later. She clears her throat, trying to interrupt the couple.

"Yes, we're new. The uh, Leroys told us about this place and we decided to check it out. Have you met them?"

"Leroys, oh yes, Bob and May. _Lovely_ couple. Come here, petal, don't stand so far away..." Kyle murmurs, getting up from the bed. He strides to Beckett, smirking at her as his hand closes around hers. "Don't be scared, Becca. We're all here to have some fun."

He leans in, lips pursed, but Beckett takes a step back, mostly on autopilot. Kyle smells of alcohol and sweat, and she's not letting him come anywhere near her. It does, however, spark her interest that they know of the victims and she needs to get the information out of him before things start spiraling out of control.

"I just, uh, hey, what were they into? Bob and May?" The back of her calves collide against the table in the middle of the room and she stumbles. Kyle narrows his eyes at her, tilts his head to the side and a cold chill travels down Beckett's spine.

"Why are you so interested in Bob and May, petal? I'm tryin'a get in the mood here," Kyle says, reaching a hand to scratch the back of his neck. "I mean, your boy over there gets it."

Her head whips around so fast and her blood boils when she spots her partner. He's backed up against the wall, with Jill draped all over him. She can't see him, but _her_ barely clad body is pressed up against his, hands splayed wide around his biceps as she nuzzles his neck.

Oh my _god!_

They're meant to be _working_ right now. The nerve of the man!

Heat courses through her veins as a familiar image flashes in her mind's eye; of him pressing up against Serena Kaye, kissing her without abandon. She balls her fists by her side, Kyle temporarily forgotten, and she stalks to Castle, fury dictating her every move.

"Hey, _husband_ , you busy?" she hisses as she nears them, nails digging into Jill's shoulder and forcing her away. "I need to talk to you."

Jill, much to Beckett's chagrin merely shrugs as she steps away. The grin that's spreading across her face is almost predatory and Beckett blinks at the unexpected reaction.

"Oh, you're a wildcat aren't you, I _like_ you, rawr!" Jill raises her hands into a claw-like shape and scratches the air in front of her. "A woman after my own heart! We can definitely play with two doms, I'll just get us set up over here."

Jill winks at her and Beckett shudders at the implication at what Jill thinks they're about to do. The blonde walks backwards towards the bed, hips swaying before she collects her husband and re-engages with him.

Beckett turns back to Castle and jabs her finger at him as she shoves him further into the shadows. She glances back at the other two, making sure they're still preoccupied and whispers angrily at him. "Oh my God, do you _have_ to kiss every woman you meet on a case, have you no self-control?"

"Excuse me, Miss 'dirty dancing with naked men', you are such a _hypocrite_! And, I _didn't_ kiss her!" Castle bites back with an angry frown, a hand rubbing over the spot where she'd jabbed him.

"Oh, you can't be serious - _I_ was trying to get us information! Dylan got us here, and these two know the vics. What were _you_ trying to achieve, huh? Find out how long she can hold her breath? How toned her legs are? Way to be professional!" she snarls at him, careful to keep her voice low.

"What, oh my god - are you _jealous_?!" his voice increases in volume as his jaw drops. His eyes narrow and she can see the incredulity shining in his eyes. "You _are_! What, of me and my _good friend_ Jill?"

"For God's sake, just shut the hell up, you're going to blow our cover!" Beckett huffs, clamping a hand over his lips.

She flushes at the feel of his stubble beneath her palm and his lips pressed against her skin. She's furious; angry at how this undercover operation is slowly unraveling before her and angry at herself for letting her emotions dictate her actions.

But mostly _ugh,_ she's mostly angry because as his lips move under her hand, there's another more primal feeling bubbling from within her and it's a little disconcerting. He's upset with her, and she's really frustrated with him, yet her _body_ is vibrating with...desire?

Oh, no, that's what it is.

She's so close to him, inches away from his face, their knees bumping against each other. The material of his pants brush against her bare legs and the contact is sinful. The steady, seductive notes emanating from the speakers does absolutely nothing to diffuse the ridiculous tension crackling between them and she exhales, slowly, tries to calm her galloping heartbeat.

Her hand slides off his jaw and the lack of space between them means her hands fall to his chest, fingers curling automatically into the fabric of his shirt.

Castle lets out a long breath of air, exaggerating as if she'd actually managed to deprive him of oxygen. He fixates low on her face, and with a jolt, Beckett realises he's looking at her lips with hooded eyes.

"If you _must_ know, Becca," his voice weaves like silk in her ears, low and gruff. Her fingers tighten around his shirt and the expensive shirt creases under her fingers, twisting in her grip. Castle doesn't seem to notice, and if he does, he's not doing anything about it. Instead, he continues to speak, stoking the embers of want glowing in the pit of her stomach.

"I found out that the vics, all of them - have regular private sessions with our hostess extraordinaire, Miss Francie herself. How's _that_ for not being professional?" Castle growls into her ear, indignance coloring his words.

Beckett nods as she ponders the piece of information but she's having trouble focusing. Heat is surging through and around her. Her fingers are still fisted in his shirt and being in such close proximity to him is intoxicating.

"So what's our next move? I don't particularly want to join them on the bed..."

His voice is the perfect accompaniment to the dulcet tones of jazz swirling around her and it's hard to remain unaffected. His broad hand has traveled up her back, warm against her spine. His head tilts forward, their foreheads barely inches apart and Beckett hears her heart thundering in her ears.

His lips are parted, supple, and in her direct line of vision. She's staring, she knows, but she can't help it. Maybe, _maybe_ if she just had a taste - just a quick nip, she'll be able to get her head back in the game. That's all she needs. All she has is the memory of their one and only kiss and as much as she denies it, it's something she can't quite forget.

She leans in, head cocked to the side, angled so she's in the right position. His fingers press into her back, pulls her that much closer and oh - they're sharing the same breath, lips a hair's width from each other and all she has to do is just move just a little bit-

"Hey, we're ready for you!"

They jump apart like they've been electrocuted, and suddenly the fog of desire fades from her mind. Everything comes back with pinpoint clarity and she takes several steps away from her partner. Beckett's cheeks are flaming, untamed passion threatening to burn her from the inside out and she grateful for the interruption that allows her to remove herself from temptation.

God, what had she been thinking? She's not ready for this, not ready for Castle and everything he stood for. He's wearing a strange expression on his face, a veil of anger and confusion over his usually more jovial features. It's unusual for him and she feels guilty for being the one responsible for putting it there.

She's itching to go to him, to wrap his hands in hers to reassure him. She's desperate to wipe the animosity off his face but she can't deal with this right now, not when they're undercover in a goddamn sex dungeon. Later; they will have plenty of time to sort out their issues once they get out of here.

Beckett clears her throat and swivels around to the other two people in the room.

She nearly chokes at the sight before her.

They're naked. Stark naked.

* * *

Thanks for reading, hope everyone is having a marvelous holiday season, and Happy New Year to all!

Tumblr: griever11  
Twitter: estheryam


	4. Chapter 4

Okay. They're _naked._ O-kay.

This isn't the worst situation she's ever been in, but it's spiralling out of her control and she needs to get a handle on it and quick. Her past experience with Vice tells her she should play along, but she has Castle with her this time and it throws her off her game. Jill and Kyle stare at her, expectant, and all too suspicious for her liking.

"Don't be shy," Jill says as she shifts on the bed, rummaging through the side table. Finding what she's looking for, she hands Kyle what appears to be a couple of pills and the man swallows them without hesitation. Jill winks and holds out her outstretched palm to them, more pills in hand.

"We can help with that if you need a little ... motivation."

Beckett purses her lips and shakes her head as Castle steps in just a little closer. "No, we're okay, just like this. We're good."

Jill rolls her shoulders, eyes narrowed into slits. Her fingers close around the capsules, doesn't take any of the pills herself, instead stashing them back into the drawer. Jill turns back to Beckett and stretches her arms over her head, back arching, easing her bare feet onto the floor.

"As you wish. Let's have some fun, then?"

She glides across the room to Beckett, smooth strides and lithe like a cat, almost like a predator stalking her prey. "You two look a little tense, what's going on here?"

Beckett bristles at the woman's tone and her brain works overtime to come up with an answer that won't send them deeper into the hole they've dug for themselves. Castle provides a comforting presence at her back; a solid wall of warmth and she draws confidence from him despite the tension between them.

She'd thought that her time in Vice all those years ago would be of some help but that usually involved her working alone, seducing men who would fall at her feet the second they laid eyes on her. This? Working with Castle, tiptoeing around him and trying to figure out what the _hell_ they were doing here? God, she's so out of her comfort zone.

She straightens anyway, realigns her spine so she stands tall and allows herself to smile, leaning further into Castle to try and feign intimacy.

"We're not, tense, just ah, just trying to -"

"- get in the mood," Castle interrupts, and a hand comes around to wrap around her waist, fingers curling around the curve just above her hipbone. "You know, get the groove going."

His words fall flat to her ears, too forced, too eager. And by the way Jill furrows her eyebrows, he hasn't convinced her either. Jill folds her arms over her chest, glaring at the partners, apprehension rolling off her in waves.

"Are you guys even married? Because you don't look like you are. If you're not, you can't be here. This club is exclusive. Francie won't like it. _We_ don't like it."

Beckett trains her gaze on Jill's face, making a point not to look any lower than she has to. Something about the steely glint in Jill's eyes unsettles her, her words setting off alarm bells in her head. An uneasiness creeps through her veins as the hairs at the back of her neck prickle over her skin and it takes every ounce of her training and experience not to give her nervousness away.

"You know, Dylan said you guys were fighting before," Jill continues. "That you were having _problems_."

Something tugs at her from the back of her mind, something about the case, but she can't quite pin it down just yet. Her thoughts are scrambled, sluggish, and it feels like she's battling through wisps of thick cobwebs stretched across her brain. She's not sure what's happening, but she needs more time. The tension in the room has increased tenfold, and Jill's threatening glare doesn't quite spell out good news for them.

"Were you stepping out on your darling husband, Becca?"

Jill advances towards Beckett and Castle, likely expecting an answer or an explanation from them. Jill stumbles a little as she strides past the coffee table but she recovers quickly, no less menacing than she was before.

As Beckett scrambles to find a suitable response, she notices Jill has a hand behind her back, out of sight and dread sinks low in her stomach. She's been in enough situations with suspects to know when the things are about to get dicey, her gut is screaming and her instincts are rarely ever wrong.

"We _are_ , we're married. No stepping out. We're fine. I promise," Castle says, but the crease along his forehead and the frantic look in his eyes indicate he's not quite at ease as he's pretending to be.

He must sense that something's off as well. They've always been in sync with each other, sharing an unexplainable mental connection that was the foundation of their partnership and this time isn't any different.

He applies a little pressure against her waist and she twists so they're standing almost chest to chest, his arm still draped in a protective bracket around her. His breathing is heavy, mouth set in a thin, grim line. He leans down, and before she can question his actions, his lips glance over the curve of her ear.

"Knife. She got a knife from the table. Pretend, Beckett, like last time." The low baritone of his voice sends chills down her spine. She barely has time to register what he means before his lips are on hers, bruising and heated as it makes every nerve ending in her body short out.

It's reminiscent of the first time they kissed - under almost similar circumstances, but at the same time, so _different_.

This time, every stroke of his tongue against hers is a reminder of his confession, of the feelings he has for her that she's pretending she's unaware of. Every shared breath means so much more, weighing down on her like an anchor dragging through a bed of sand. She groans into him, her heart warring with her brain. Every responsible fibre of her being is yelling at her to stop, right now, and to deal with the imminent danger, disarm Jill, get the hell out of this skeezy place, but she can't.

She physically _can't._

Her fingers splay wide against his cheeks, pulling him into her as if he can get any closer than he already is. His hands, broad and all-encompassing, clutch the back of her dress, scrunching the material in his palms and she shivers at the contact.

She sneaks her tongue between his teeth in retaliation, sliding it against the roof of his mouth before sucking on his lower lip and scraping the edge of her teeth against the soft flesh. He moans, chest rumbling as he fits a thigh between her legs, ruffling the skirt of her dress. The smooth material drags up her skin and heat pools low, electricity shooting through her.

He's mumbling something; frantic, maybe even important, yet it's all unintelligible syllables pressing against her lips, feathering against her subconscious, but nothing clicks. Something's wrong, _very wrong,_ because it's like she's drunk but she hasn't had any alcohol tonight. Yet, all she can think of his the way he feels against her like she has tunnel vision and at the end of the tunnel is him and only him. And his mouth, his hands, and his leg between her thighs-

And then everything vanishes.

His lips are gone, and his hands leave her back too. They slide up her shoulders and he spins her, hard. She blinks, trips over her own feet as she whirls around, trying to maintain her balance.

Beckett gasps and regains her footing, only to see Jill lunging at them, the knife held high ready to strike. Castle rips across the room, tackling her to the ground. Beckett stands dumbfounded, staring at the scene unfolding before her, breathless.

"NYPD! Sort of!" he yells, his voice booming over the sultry tones of the music playing in the background. "Stay on the floor!"

His bulk obscures most of Jill's torso from her view, but she can see that he's pinned her to the ground face first, wrestling the knife out of her hand.

Kyle's slipped off of the bed, the effects of whatever he took earlier impeding his senses as he lands on all fours, panic bleeding from his eyes. He alternates between trying to stand up - but failing - and shouting at no one in particular, incomprehensible words spilling from his lips.

The chaos triggers something within her, the churning in her gut dissipates just as quickly as the heat that had engulfed her mere seconds before and it kicks her into action.

Lurching forward, she elbows Castle, taking over as she kneels to hold Jill down against the floor. Castle spares her a glance, deep lines etched into his forehead as he tilts his head. They don't speak, but understanding flashes across his face and he leaps to his feet and darts over to Kyle once Beckett has a firm hold on Jill.

The woman writhes beneath her, and Beckett grits her teeth as she presses her palm against the bare skin of Jill's back just above a small tattoo of a swallow, her knees digging into the plush carpet. Her other hand dips into the neckline of her dress and pulls her badge out, the metal warm from being nestled against her skin all night.

"NYPD, stay the hell down."

She cranes her neck, spies the knife glinting in the low light a few feet away and she stretches a leg to slide it further out of reach.

Castle, on the other hand, seems to have managed to subdue Kyle, hauling the still very naked man to his feet, hands pulled tight behind him. Beckett clears her throat, her position kneeling on the ground putting her in the direct line of sight of Kyle's...

 _Business._

The room shimmers before her, the lust and desire that colored her vision fading. She's struck by the sudden clarity of the situation before her and she blanches.

She made out with Castle.

Her tongue was down his throat.

While their lives were in _danger._

What had she been _thinking?!_

Of all the things she's done as a cop, from her early days as a rookie, this has got to be one of the most unprofessional, negligent, most-

"Beckett, a little _help_ here?"

Her eyes flick up to his and widens as she realizes Castle's barely holding on to a struggling Kyle, his grip slipping each time the guy moves. He stares at her and jerks his head, an expectant look on his face.

"Oh uh, yeah. Sure," she mutters. She places a knee on the center of Jill's back, careful to not put too much pressure and she slips a hand under the hem of her dress. She unclips the handcuffs from her thigh holster and tosses it to him, grinning when he catches it one-handed.

Laughter bubbles beneath the surface as she finally takes stock of their predicament, a mixture of relief and nervousness replacing the adrenaline that had been coursing through her veins. It's ridiculous; pure absurdity that they've ended up here, considering they started the night off with nothing much more than 'Hey, we're married, let us into your sex club so we can _maybe_ get a couple of leads'.

"Get off me, you bitch," Jill snarls from under her. Beckett rolls her eyes and presses her knee harder into the woman's back for sheer measure.

"Shut up," she retorts. Her cuffs are with Castle and she's at a momentary loss at how to keep the other woman in check until she hears the clink of metal against the floor.

A pair of fluffy pink handcuffs slide towards her and a bark of a laughter escapes from between her lips. Castle grins, dragging Kyle over to the bed and dumping him unceremoniously onto it.

Beckett makes quick work of the cuffs and stands up, pulling Jill up by her wrists. She sits her next to Kyle, and after a moment of thought throws a blanket at them. "I've seen enough of you two tonight," she mutters.

The defiance on Jill's face tells her that she's not getting anything out of her anytime soon, so Beckett shoots her one last withering stare before stepping away, motioning with her fingers for Castle to join her.

"I called the boys, they're on their way," Castle says, a glimmer of worry in his eyes. "Are you okay?"

"Yeah, I'm fine, and uh, thanks," Beckett pauses, the phantom feel of his lips and his tongue invading her mouth rushing back to her. She feels her cheeks warm up and she licks her lips, shaking her head. "For the save, I mean. For taking her down."

Castle nods, but he doesn't smirk at her like she expects him to. Instead, he seems concerned, eyebrows furrowed. "What happened there anyway, Beckett? I was trying to tell you ... but you seemed a little out of it. Like you were drugged..."

She appreciates that he's not making a bigger deal of their spontaneous kiss - for now - but her heart warms at just how worried he is. He does have a point though and she blinks, allowing herself to take a moment to assess her own well-being.

Yeah, she still feels a little sluggish and it's disconcerting. She concedes she might have been drugged, but she's not sure how. Maybe it was the drink she had earlier, but that had been a while ago and she'd only felt the effects within the last half an hour.

Once again, she feels like the solution is _right there_ , just out of her reach. She'd had the same feeling earlier, something about the case so close within her grasp and if her brain would just _work_ properly ...

Oh. _Oh._

She blinks as realisation sinks in, the pieces of the puzzle finally falling into place and she gasps in horror.

Castle frowns at her reaction, but as usual, it only takes a second before he follows her train of thought and his jaw falls open as well, clarity in his eyes shining through.

"Oh my god," he whispers. "Beckett, _no way_!"

They both share a look, understanding dawns over their features as together they slowly look up at the ceiling, heads tilting up simultaneously searching for the-

"Vents," they groan at the same time. "Pheromones through the vents!"

* * *

 _Many thanks to the lovely ladies who_ beta'd _this for me, saving this chap from an excess of flat falling and shoulders. Thanks for reading, hope you're enjoying! I'm giving away a couple of stuff over on Tumblr to commemorate a follower milestone, so if you're interested, please go on over to have a look! Again, thank you for reading and all your feedback/reviews are much appreciated!_

Twitter: estheryam

Tumblr: griever11


	5. Chapter 5

It's pitch black when Beckett and Castle finally emerge from the club, feet dragging against the asphalt as they carry their exhausted selves out the door. Ryan and Esposito follow closely behind them, herding their two still protesting suspects out the premises.

Beckett's whisked away the moment the paramedics spot her, bundled up in a thick blanket and instructed to take a seat on the metal steps at the back of one of the ambulance. They leave her be once they're sure she's relatively okay and not going anywhere, rushing off to tend to Jill and Kyle.

In the dark of night, the flashing blue and red lights are almost blinding, pulsing in even beats in the corners of her eyes. She's had to go through this so often - more often than she'd like, that she really doesn't have the patience for it anymore.

She looks around while she waits for someone to come back to her and spots her partner standing a few feet away, deep in conversation with Ryan and Esposito. His hands are waving wildly in the air as he speaks, presumably giving them his statement. She makes a mental note to review their reports later, knowing that Castle's version of events will probably contain a lot of irrelevant, exaggerated details of what went down in the room.

Someone clears their throat and Beckett pulls her eyes away from the trio, turning around only to be confronted by a familiar face. The paramedic is a young man she's seen more than a few times at her crime scenes, and she stifles a groan. Doug reminds her of a younger Castle, which only means that unfortunately for her, he won't be afraid to tease her about the circumstances of how she ended up at the back of his van.

"Always getting into trouble, aren't you, Detective Beckett? Freezers, tigers, being drugged by pheromones...It's always so much fun when we get call outs from the twelfth. Look here, please."

Doug shines a bright light in her eye and she grunts, trying to turn away from the offensive glare. He knows her far too well for her liking though, anticipating her move and his fingers tighten against her chin to hold her in place. Sighing, she gives in and stares into the light.

"Hey, you know what? I'm totally fine, Doug," she mutters. "You should go check on the others."

Doug shrugs, ignoring the frown on her face. "My colleagues are taking care of the others, don't worry. Mr. Castle insisted that we do a thorough check on you." He winks at her and smirks before continuing. " _He_ seems to think that for some reason, the pheromones had a more severe effect on you two than the other couple."

"Oh my God! It did _not_ affect us more than it did them. We were affected _the same_ ," she hisses, eyes cutting towards her partner as she glares at his broad back _. Of course,_ he'd tell them of their little...incident. Smug bastard.

"Well, Mr. Castle was adamant that we make sure you were fine, he said you were a little dizzy before," the paramedic says, unperturbed. "And he's not wrong. It could have affected you differently than the others."

"What? _Excuse me_?" Beckett swats the man's hand away from her cheek, her voice laced with incredulity. Is he agreeing with Castle? It's not something that happens very often and it piques her curiosity. "You're saying Castle's crackpot theory has some merit?"

Doug sighs as he packs his equipment away. "Well, yes, to a point. The way pheromones work depends on a person's, or a couple's, pre-existing relationships. To put it simply, if a person A feels comfortable enough with person B, the likelihood of feeling the full effects of the hormone is significantly higher than if two complete strangers were to be doused with it and put in the same room together."

"That means–"

"It means, seeing as how you and Mr. Castle were already partners and very familiar with one another, you both would have been more susceptible to the pheromones and its effects."

 _Oh._

Oh, well then.

Doug continues to ramble on but whatever else the paramedic says fades into the background as she contemplates the new found information. It explains a lot of what had transpired earlier in the night; the inability to control herself around Castle, his sudden burst of overprotective bout of jealousy, their impromptu make-out session.

It's all starting to make sense now.

Doug slings his bag over his shoulder, motioning for her to get off of the metal steps at the back of his van. "Well, Detective, you look like you're in perfect health, so I'll leave you to it. Oh, here's Mr. Castle!"

Heavy footfalls approach them signalling Castle's arrival. She thanks Doug, albeit begrudgingly – she didn't even need him to check up on her in the first place – and steps away from the van, turning to face her partner.

"Everything alright?" he asks. He cocks his head to the side, waggling his eyebrows. "Not still high on sex hormones are you?"

Beckett scowls at him, his cheeky, flippant tone grating on her nerves. He was nearly stabbed by a homicidal nymphomaniac not too long ago and here he is joking about it like his life hadn't been in danger. She sighs, mutters a few choice words under her breath before nudging him out of her way so she can get to her Crown Vic parked by the side of the road.

He isn't phased by her dismissal and falls in step with her easily enough, his long legs matching her stride for stride. "Are you really okay, Beckett? I only ask because you didn't look too well before and I've already given my statement so I'm sure Ryan and Espo can cover you for you if you need to go home and-"

Beckett cuts him off, whirling around on the balls of her feet and coming to an abrupt stop mid-step. "Hey, I'm fine. Perfectly fine. They were pheromones. We were doused with just pheromones, okay? Can you stop being a big baby about it and just let it go?"

Castle stumbles, managing to catch himself before he collides into her and frowns. "I'm just looking out for you, Beckett," he mutters.

"I don't need you looking out for me," Beckett argues. "I'm the cop, remember? This is my _job_."

She knows she's said something wrong when his expression falls and weariness takes over his features. He runs a hand over his face and then into his hair, dejected.

"I know you hate the idea of needing help; have to be Miss Independent all the time. But all you've done is snap at me all night. Give me a break. I'm sorry if I get worried about my partner sometimes," he spits out.

His words catch her unaware and she stands rooted to the spot, mouth parted in surprise. She doesn't expect the honesty that pours out from his mouth. She doesn't have a ready answer for him and Castle takes the opportunity to barrel on.

"Why do you even keep me around anyway? For a convenient make-out session whenever it suits you? Are you going to forget about what happened tonight like the way you forgot about the last time we kissed? Is that what's going to happen here?"

His chest is heaving by the time he's done and Beckett's own heart is thundering in her ears. Her cheeks heat up with the realization that he's right and that she's being completely unfair - but all she can do is stare open-mouthed at him. She's not sure if she's still battling the side effects of the pheromones - she feels fine, after all - but somehow, she's finding it hard to form the words she so desperately wants to say to him.

Yes, okay, she'll admit she had been short with him most of the night. He was only being cautious, and she can understand that, now the frustration that had plagued her all night has ebbed away. Biting his head off and telling him to leave her alone - yeah, definitely not one of her proudest moments.

Castle remains silent only a few feet away from here, although they might as well be standing miles apart. He's shooting her a heated glare, his jaw clenched, fists curled by his side. The product in his hair is long gone, leaving the thick strands falling flat against his forehead. His dress shirt, ironed and immaculate mere hours before, is now rumpled, untucked and he looks so completely dishevelled but-

God, even when he's upset with her, he's still a sight to look at.

As much as she tries to deny it, she's always been attracted to the broad width of his body. He's big and tall, a perfect complement to her own slender frame, and despite living the lavish life of a millionaire writer, he still exudes strength from every muscle in his body. It appeals to her baser instincts, the primal need to find a partner that can keep her satisfied, both physically and emotionally.

Eventually, his shoulders slump forward, tension dissipating as he inhales deeply. A rueful smile crosses his face. "Okay, forget it. You're fine, I'm fine - let's just get back to the precinct so we can wrap this up. It's getting late and I'm cold."

Beckett blinks, stunned by the sudden change in his demeanor. The wind picks up around them, howling in her ears and blankets them in a whisper of cool air. She needs to apologize to him, that much is clear, but Castle also had a point. They still need Jill and Kyle's confessions and despite the heaviness in her heart, that should be their highest priority right now. She'll make it up to him after - she'll make sure of it.

Sighing, she nods at Castle, walking to the driver's side of her car. He takes his usual place at the passenger side door and avoids looking at her as he slides into his seat. Beckett bites her lip, rolls her shoulders and ducks down into the car.

It's going to be a _long_ ride back.

* * *

In the end, faced with the unrelenting force of Beckett's interrogation skills, the two suspects break down and sing like canaries about the darker side of their hedonistic pleasure. It's almost two in the morning when Beckett emerges from questioning them, alone - Castle had excused himself from joining her in favor of wrapping up the finer details of their night with Ryan and Esposito. She'd been a little hurt at his decision but she doesn't blame him. She has their signed confessions in hand, and that's what matters for the time being.

She leans against the door, head bowed down as she tries to ease the kinks in her lethargic neck muscles. The case against them both - Jill mostly, and with Kyle as an accessory to murder - is pretty solid, but both of them will probably cop an insanity plea, and even if that's not the most ideal of outcomes, it's better than nothing.

L.T walks up to her and she nods, signing off on the paperwork he hands her so he can escort the two suspects to holding. She walks away from the door, allowing L.T to enter, and turns the corner into the bullpen, heading back to her desk.

She hears a chair scrape against the wooden floor and her head shoots up, not expecting there to be anyone left except the late night skeleton crew.

Castle. He's still here. He waited for her. A rush of warmth shoots through her body and suddenly she doesn't feel quite so tired anymore.

He blinks at her with inquisitive eyes, eyebrows arched as she approaches her desk. "How'd it go?"

Her tongue trips over the words she wants to say, and she has to clear her throat twice before her lips catch up to her mind. "Uh, exactly as we thought actually. Jill used the club as her hunting ground for couples with relationship problems, cheating spouses, whatever, and set the trap - used Kyle if she had to. "

"It's a swingers club," Castle says frowning. "Wouldn't everyone there-"

"She's specifically targeting couples who went through the same thing she did. Jill and her ex-husband had a rather tumultuous relationship and it ended a year ago with him taking out a restraining order against her," Beckett repeats the information, still perturbed at the ease of how she managed to get them to talk.

"She's been trying to win him back ever since, but two months ago, he got diagnosed with Stage 4 cancer and somehow Jill must have snapped, decided if she couldn't get her happy ending with him, then she'd go after anyone else who didn't appreciate being in their own relationship." Beckett raises an arm to brush her hair out of her eyes, limp strands falling over her forehead. It all still doesn't quite make sense to her, but until evidence proves otherwise, she's confident that they're the culprits.

"Jill met Kyle at group therapy, go figure, and somehow convinced Kyle that murdering these couples would help get them out of their depression. Kyle's so jacked up on drugs I don't think he realizes what's going on most of the time anyway. I've put in a request for a psych eval done on both of them - they're definitely not completely all there, if you know what I mean."

A thoughtful look flits across Castle's face as he digests the information. "Huh. Okay, so...our fight, when you were dancing..."

Beckett nods, catching on to his train of thought. "And when she asked if you were stepping out on me - she was deciding if we were going to be her next targets."

"That's _crazy_."

"Hey, we've had worse," Beckett offers with a grim smile. The fact that they've been in so many life-threatening situations is really nothing to be smiling about, but the fact that they've survived them all is still something to hold on to.

Beckett eyes the pile of papers on her desk and sighs. She has to finalize her reports, go through Ryan and Esposito's and process the arrest but god, she's so tired. The emotional roller-coaster she's been on all night thanks to those damn pheromones has taken a toll on her and all she wants to do is go home and pass out on her bed.

The exhaustion must be evident on her face because Castle's already picking up her bag from the floor, easing the long strap over his shoulders. It's a little presumptuous of him, but she can't find it in herself to argue - the paperwork can wait.

"I'll walk you out?" Castle asks, tentative, as if there was a chance she'd say no - he's already holding out her coat for her, spread open so she can slip her hands into the sleeves. She turns her back to him and pushes her arms into the thick material of her coat, welcoming the instant warmth that envelops her.

The warmth that has absolutely nothing to do with the fact that her back is a hair's width away from his solid chest. Nothing to do with the fact that she can feel him breathe against the skin of her neck, or the fact that his fingers are currently traveling up the sleeves of her coat, a tingling sensation rippling up her arm until they stop at the collar. Nope, not at all.

"There you go. No more freezing Beckett."

The lightness in his voice isn't genuine, and Beckett picks up on it immediately. She turns around to face him, taken aback for a moment when she realizes how close she is to him. A slight stubble has formed along his jaw, and she's suddenly itching to run her fingers over his skin - wants to see if it'll feel good in contrast to the smoothness of her own. The smile that graces his features doesn't quite reach his eyes and it's telling of how he really feels beneath this facade of pleasantry.

She wants to fix this.

Them. She wants to fix _them._

He's still not over their mini-spat outside the club, that much is clear and honestly, neither is she. She bites her lip, quells the bone-deep weariness threatening to take her under and makes her decision.

"Castle, I think ... I think we need to talk."

* * *

Beckett contemplates going to Remy's, almost giving in to the call of their delicious milkshakes and cheeseburgers, until she realizes that Remy's is their safe place and she doesn't want safe right now. Castle's upset with her, and despite the churning in her gut and the nervous butterflies fluttering in the pit of her stomach, she's going to do everything she can to remedy that. He deserves more than their usual subtext-laden conversations and for once, she's going to take Dr. Burke's advice and just...leap.

She takes his hand with renewed determination, fingers curling around his much larger ones. She feels his hesitation, the slight jerk of his palm at the contact, but she ignores it. She doesn't look at him - not yet - instead, striding with purpose past him, tugging him along with her. It's a short walk to the place she has in mind, and despite the unusual bubble of silence around them, hope sparks within her.

The park is as quiet as death when they get there. She sniggers in her head at the Castle-like pun, but sobers when Castle comes to a sudden halt behind her. Her hand slips out of his and she turns to look at him.

"What are doing here, Beckett?" he asks. He tilts his head at her, eyebrows furrowed as he fixes her with a curious gaze.

"I just wanted to talk," she says, clenching and unclenching her fists. "I, um, wanted to make sure we weren't interrupted."

She makes her way to the swing set a few feet away, the same set where they had their first conversation after she spent three months recovering in isolation. She's haunted by the images of their past selves and it dawns upon her that they're in almost exactly the same situation now as they were then; with Castle and the bubbling anger beneath the stubborn set of his jaw, and her desperate to reconnect with him.

Hm. Funny how things work.

She sinks into the thick plastic seat, the metal chains clinking as she settles in, indicating with her head for Castle to do the same. Her feet brush against the ground, her tips of her shoes give the dirt a gentle push, allowing her body to sway back and forth.

"I'm really sorry, Castle." It's a good start as any, she thinks. Her fingers wrap tighter around the cold metal chains as she inhales. "For tonight. Snapping at you when you were only watching my back - you're right, that wasn't fair."

"It's okay, Beckett. You were frustrated, you were following my dumb plan, I get it," he mumbles. He's sincere about it, that much is evident in his voice. But there's a sad tinge behind his eyes and it's unnerving.

"Hey, your dumb plan helped us catch the bad guys, so...as far as dumb plans go, I think that was one of your better ones." She's trying to inject some levity into the situation, but it falls flat and she squirms in place.

Now or never, Beckett.

"Castle, I don't want to forget about our kiss."

Her voice is barely above a whisper, but she can tell he heard her. Swallowing the urge to turn around and run as far as she can, she ploughs on. "I don't want to forget about _any_ of it. You're right. It's unfair. On you, on _us_. You're...you're my partner, yes. But... you're also _more_ ," her voice strengthens with every word that tumbles from between her lips. It's everything she's wanted to say ever since he walked into her room at the hospital with his perfect hair and the wonderful bouquet of flowers in his hand.

"I care about you and I have a horrible way of showing it, I know." Her eyes stare into his, pleading with him to believe her. "I'm working on it, I promise. I'm not...where I want to be, not yet - but I think maybe I was wrong before."

"Wrong?" Castle finally speaks, his one single word echoing in the night. His face is softer, gone are the hard lines from before, replaced instead with an openness she hasn't seen in awhile. "Wrong about...me?"

"No, wrong about _me_. About needing to wait. I don't wanna wait anymore, Castle." She breathes out, slow and steady. Her throat feels dry and her tongue darts out to wet her lips. She's nervous. She's so very scared about what she's about to do, but at the same time, she's _soaring_. Her heart has never felt this ... free in a long time and it gives her the confidence boost she needs.

She stands from her seat, hands gliding up the chains, and she's glad to see that Castle's followed suit, eager, with pure, unadulterated hope reflecting behind his blue eyes.

"Castle."

It's the last word out of her mouth before she takes a step forward and reaches out to him. Her hands seek the warmth of his body, slipping around his neck and she presses her mouth against his for the second time that night.

His lips are cold against hers but she doesn't care - she'll keep him warm. The way he tastes is exquisite; a delicate mix of coffee and chocolate - it seems he'd been digging into her stash at the precinct while he waited for her. When he groans against her it sends tingles down her spine and a strange but welcome rush of heat blooms from the centre of her heart. He's soft and pliable against her, tongue probing for entrance between her lips and she grants it to him without preamble.

Everything is electric. He's not holding anything back, teeth clashing, tongues dueling. His nose nudges hers and she shifts, changing angles, her mouth falling open even wider to drink in everything he's offering. His broad palms have snuck under her coat, resting along her spine, pressing her body against his. She fights the urge to hike her leg up around her waist, but she does slip a thigh between his and - oh.

Oh.

He's excited.

She pulls away, lips parting from his with reluctance, resting her forehead against his. Her heart is racing, can't decipher one individual beat from another other. The undercurrent of desire is coursing through her veins like embers about to evolve into a fiery blaze. Her thumb comes up to his neck, rests against the pulsing vein under his skin and she's delighted when she feels the same raging beat of his own heart.

"You don't think the pheromones spread all the way out here, do you?"

Beckett lets out a bark of laughter at his question and leans back biting her lips. He's so beautiful, the sadness and misery from before completely gone, replaced with absolute mirth.

"No. No pheromones. Just me. And you," she replies. She steps back, grinning at him. She feels so much lighter, so _happy,_ and all she wants to do is to curl up in his arms and bask in the new sensations he's evoking within her.

Her hand falls away from his neck, reaching down instead for his warm digits. She twines her fingers between his and smiles.

"Come home with me."

* * *

 _Only the epilogue left and that will be M rated, so if you're not into that, then this is the end! Many thanks to beta squad and also to all of you for reading and reviewing!_

 _Twitter: estheryam  
Tumblr: griever11_


	6. Epilogue

Please note that chapter is rated M.

* * *

Epilogue

When Beckett wakes up, she finds herself sweltering, her skin damp with sweat and her hair sticking to the back of her neck. She's confused at first because it's the tail end of winter and usually her toes are freezing in the morning but today she's woken up feeling uncomfortably warm.

She huffs in frustration, trying to fight through the cobweb of sleep she's still trapped in. Her muscles are sore and she moves slowly as she rolls onto her back, only to find there's a solid barrier behind her. She panics for a moment, heart clenching at the unknown until she remembers how the events of the night before unfolded and she relaxes.

Castle had returned home with her the night before, eager and humming with anticipation the entire cab ride back to her apartment. He'd been surprisingly well-behaved, not even a single finger out of place the whole twenty minutes, but when they arrived and from the moment she unlocked her front door, they'd been inseparable.

A smile stretches across her face and all of a sudden she's flooded with childlike excitement. She still has her back to him, but he's draped an arm around her waist, his palm having slipped under her sleep shirt sometime during the night, warm against her skin.

Castle's still here.

"Mmm, Beckett."

And he's awake.

Beckett lifts his arm off of her so she can turn to face him. "Hey," she greets him, grinning. "Morning."

The edges of his eyes crinkle in delight and he scoots closer as if he's not already half draped over her. He nudges a leg between hers and she accommodates him without hesitation, more than willing to be cocooned within his embrace despite the heat emanating from him.

"You're so pretty," he whispers. He's staring at her with disbelief glimmering in his eyes and it makes her blush, warmth creeping up her cheeks. It's not that she's unaccustomed to compliments from him, but the intensity of his gaze and the sincerity that coats his words, especially after the night they've just had - it means so much more now.

"And you're so sappy," she counters half-heartedly. She runs a finger along his bicep, chuckling when she sees the goosebumps erupt on his skin. He'd foregone putting on a shirt last night, even after she warned him that her room has a tendency to get chilly. She'd rolled her eyes at him then, but now she knows why. The man is a human furnace, so very hot.

"I know I'm hot, but thank you for the confirmation," he says around a smirk, eyebrows arching at her.

Oh, she said that out loud, did she?

Beckett laughs, full and hearty - because oh god, she's so happy it's ridiculous. She rolls away, ignores the soft "hey!"' from Castle and kicks off her covers. She's hit with a blast of cool air and she welcomes the sensation. Castle pouts at the space she's put between them and she rolls her eyes at him. "You're turning my bed into an oven, Castle. I need to cool down."

Her explanation seems to fall on deaf ears because it doesn't deter Castle from inching further into her personal space. His fingers creep along her waist, finally resting against the middle of her back.

"Do I make you feel hot, Beckett?" He doesn't even blink at the sheer cheesiness of his line, instead, he leers at her with focused intent. His fingers slide lower down her spine and the crisp blue of his eyes darkens. "Hot and bothered?"

She doesn't dignify his teasing with an answer but swallows at his ministrations and raises her own fingers to trail along the sharp angle of his jaw. The stubble that's grown overnight is rough under her skin and she licks her lips as she imagines the same coarse sensation between her-

"I know what you're thinking about, Beckett." His voice cuts through her straying thoughts, and as if she's a child caught with her fingers in a cookie jar, she blushes again. The mischievous twinkle in his eye indicates that he might actually know, and when he rolls over her moments later and nuzzles her neck, stubble scratching against her skin, she's sure he does.

Beckett welcomes his weight over her body, groans at the skin-on-skin contact that ignites a slow burn from deep in her belly. She doesn't have time to think about what he's doing, but when lifts his head from her neck and his lips press against hers, she finds that she doesn't care. She opens up to him willingly as his teeth graze along the soft flesh of her bottom lip. Her tongue darts out to meet his and she sighs into him, melting into the desire bubbling between them. He tastes sweet and she takes her time to savor the flavor she's fast getting accustomed to.

She takes her time with him, pulls him closer just as he slides a leg between hers. The contact provides just the right amount of friction exactly where she needs it and she lets out a strangled moan. Her thighs clench around his leg and keep him there, hands drifting down his ass to hold him in place. His excitement is solid and insistent between them, making her toes curl with anticipation against her sheets.

Castle pulls away momentarily and she protests the temporary separation, but he skims his jaw along her cheek and the words disappear. All she can do is groan again at the prickling of his stubble on her skin as he busies himself exploring her body. She drags her hands up, nails digging into his back, urging him on, forearms pressing along the ridges of muscle between his shoulder blades.

"Told you I knew what you were thinking of," he whispers, placing open-mouthed kisses along her collarbone before trailing a wet path downwards. He drags his palms down her sides, scorching down the edges of her ribcage, spreading his fingers wide on her waist.

An uncharacteristic mewl leaves her lips at the surge of heat racing through her entire body and Castle chuckles, low and throaty in her ear. "Am I still making you hot?"

His right hand slides lower, and then lower still, and when the he slips a finger along her already wet folds, she lets out a sob of relief and bites down on his shoulder. She raises her left leg, curls it around his lower half and digs her heels into his ass cheek, giving him room to move.

Back and forth, he repeats the motions, first with one finger, then two - but he doesn't quite enter her, exasperating man - but the repetition adds fuel to an already blazing fire and she's so close. So damn close, all she needs is-

Oh. _That._

Reading her just as well as he does when they're not naked and breathless, he plunges two thick fingers into her and Beckett has to bite her lip to hold back the feral scream that threatens to pierce the hushed silence between them.

She's already so worked up that she doesn't think it'll take much more to have her shattering under him but she sighs and does all she can to hold on. Her heart thunders in her ear, deafening, and her hands slide off his back to clutch the sheets, twisting them between her fingers, anchoring her. She's teetering on the edge of oblivion, getting closer to losing all semblance of control with every press of his thumb against her clit.

Her body is writhing unashamed underneath him, urging him on, thighs clenched around his solid-

"You definitely feel hot enough, Beckett."

"Oh my god, do you ever shut up?" Beckett growls with impatience. Her left hand leaves the death grip on her sheets to palm the side of his face, guiding his lips towards her mouth once again. The kiss she steals from him is breathtaking and bruising, punishing even, and it makes her think of how it mirrors their partnership outside the bedroom.

A thrill shoots through her at the thought, and she bucks under him, her hips lifting, grinding. She needs him, she's desperate with want, inner muscles squeezing his buried fingers, wishing, wanting it to be more.

"More, Castle, more, please," she begs eventually. She's not afraid to ask for what she wants, and it seems to be what he's waiting for because with one last pass over her clit, he removes his fingers from her and grins, wide and mischievous.

"As you wish," he smirks. He rises up on his knees, hands guiding her legs so they circle his hips and with an exaggerated wink, he slides home.

Everything from then on becomes a haze of pleasure, a blur of thrusts and simultaneous groans. They move instinctively, far from the languid, sensuous controlled build up from before. They've only done this once...no, twice before, but everything is already so perfect, and her body shudders with a visceral response, moving with him as they chase their mutual high.

Castle sets a punishing pace but Beckett's right there with him, matching him thrust for thrust, taking him deeper with every slide of his hard length into her. Beckett cries out his name, repeats it over and over and she's sure she's going to lose her voice. She's already anticipating the blinding pleasure she's about to succumb to, expects it to crash around her like waves along the shoreline and she gasps, loud and unabashed when it finally does.

She tenses under him as she rides it out, eyes clenched shut, arms tight around his upper body. Pinpricks of light bloom beneath her eyelids as pleasure races through every bone in her body. Her nerves tingle as she clutches him tight against her as if she needed him to tether her to the Earth.

Castle's chanting her name above her, breathless, and she can feel his muscles rippling under her fingers, trembling with barely controlled restraint as he climaxes. Her mouth is still fused to his neck and her heart's racing when Castle stills and groans into her ear, mumbling nonsensical words into the air, entirely spent.

They lie motionless together after, Castle resting on his forearms, head pillowed on her breasts as they catch their breath. Beckett grins and sighs, cradling his head, carding her fingers through the soft strands of his hair. She's so blissed out she doesn't even feel uncomfortable the fact he's half draped over her, tendrils of heat once again unfurling between them, encompassing their bodies.

Eventually, Castle rolls off her and slips out, an equally blissed out grin adorning his face. Smooth as ever, he raises an arm to curl around the back of her neck and pulls, cuddling her into his side.

"You know what?" he asks as his fingers trace invisible patterns on her shoulder.

Beckett lifts her gaze to meet his eyes, taking note of the cheeky spark reflected in them and she rolls her eyes, a little wary. "What?"

"I bet we'd make good money if we bottled our pheromones and sold them to sex clubs."

* * *

End.

* * *

 _Thanks to every single one of you who have read and reviewed. I hope you all have enjoyed this as much as I enjoyed writing it. I also hope this was an adequate enough birthday present, Lou!_

 _Hugs and kisses to my beta team, I love you all!_


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